/* Light palette is the default; dark is applied via html[data-theme="dark"]. */
:root,
:root[data-theme='light'] {
  --bg: #eef2f7;
  --bg-elev: #ffffff;
  --bg-soft: #e4ebf3;
  --panel: rgba(255, 255, 255, 0.78);
  --border: #c3cedd;
  --border-strong: #7f94ad;
  --text: #0f172a;
  --text-dim: #5b6b7f;
  --accent: #0284c7;
  --accent-strong: #0369a1;
  --accent-soft: rgba(2, 132, 199, 0.12);
  --good: #059669;
  --bad: #dc2626;
  --warn: #d97706;
  --note: #64748b;
  --given-bg: #e2e8f0;
  --user-bg: #e0f2fe;
  --peer-bg: rgba(2, 132, 199, 0.08);
  --same-bg: rgba(2, 132, 199, 0.16);
  --conflict-bg: rgba(220, 38, 38, 0.14);
  --cage: #6b8eae;
  --on-accent: #ffffff;
  --shadow: rgba(15, 23, 42, 0.12);
  --glow-a: #c7e0f5;
  --glow-b: #d5ebe6;
  --cell: 2.55rem;
  --radius: 10px;
  --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --mono: 'Cascadia Code', 'SF Mono', ui-monospace, monospace;
}

:root[data-theme='dark'] {
  --bg: #0f1419;
  --bg-elev: #1a222c;
  --bg-soft: #243040;
  --panel: rgba(26, 34, 44, 0.72);
  --border: #334155;
  --border-strong: #64748b;
  --text: #e2e8f0;
  --text-dim: #94a3b8;
  --accent: #38bdf8;
  --accent-strong: #0ea5e9;
  --accent-soft: rgba(56, 189, 248, 0.12);
  --good: #34d399;
  --bad: #f87171;
  --warn: #fbbf24;
  --note: #94a3b8;
  --given-bg: #1e293b;
  --user-bg: #0c4a6e;
  --peer-bg: rgba(56, 189, 248, 0.08);
  --same-bg: rgba(56, 189, 248, 0.18);
  --conflict-bg: rgba(248, 113, 113, 0.18);
  --cage: #7c9cbf;
  --on-accent: #04121c;
  --shadow: rgba(0, 0, 0, 0.4);
  --glow-a: #1e3a5f;
  --glow-b: #164e63;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  background:
    radial-gradient(1200px 600px at 10% -10%, var(--glow-a) 0%, transparent 55%),
    radial-gradient(900px 500px at 100% 0%, var(--glow-b) 0%, transparent 50%), var(--bg);
  color: var(--text);
  font-family: var(--font);
}

button,
select {
  font: inherit;
  color: inherit;
}

.app {
  max-width: 1100px;
  margin: 0 auto;
  padding: 1rem 1.25rem 2rem;
}

.header {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent), #818cf8);
  color: #0b1220;
  font-weight: 700;
  font-size: 1.1rem;
}

.brand h1 {
  margin: 0;
  font-size: 1.35rem;
  letter-spacing: 0.02em;
}

.top-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  align-items: end;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  font-size: 0.72rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.field select {
  min-width: 7.5rem;
  padding: 0.45rem 0.55rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-elev);
  color: var(--text);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg-elev);
  color: var(--text);
  cursor: pointer;
  transition:
    background 0.15s,
    border-color 0.15s,
    transform 0.05s;
  user-select: none;
}

.btn:hover {
  background: var(--bg-soft);
  border-color: var(--border-strong);
}

.btn:active {
  transform: translateY(1px);
}

.btn.primary {
  background: linear-gradient(180deg, var(--accent), var(--accent-strong));
  border-color: transparent;
  color: var(--on-accent);
  font-weight: 650;
}

.btn.primary:hover {
  filter: brightness(1.05);
}

.btn.toggle.on {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent) 35%, transparent);
  background: var(--accent-soft);
}

.btn .key {
  display: inline-grid;
  place-items: center;
  min-width: 1.25rem;
  height: 1.25rem;
  padding: 0 0.25rem;
  border: 1px solid var(--border-strong);
  border-radius: 4px;
  font-size: 0.7rem;
  font-family: var(--mono);
}

.main {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 280px;
  gap: 1.25rem;
  align-items: start;
}

@media (max-width: 860px) {
  .main {
    grid-template-columns: 1fr;
  }
}

.board-panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  backdrop-filter: blur(8px);
}

.board {
  display: grid;
  justify-content: center;
  gap: 0;
  margin: 0 auto;
  user-select: none;
  touch-action: manipulation;
}

/* Skyscrapers edge clues */
.sky-frame {
  display: grid;
  grid-template-columns: auto auto auto;
  grid-template-rows: auto auto auto;
  justify-content: center;
  gap: 0.15rem;
}
.sky-clues[hidden] {
  display: none;
}
.sky-frame > .board {
  grid-column: 2;
  grid-row: 2;
}
.sky-top {
  grid-column: 2;
  grid-row: 1;
}
.sky-bottom {
  grid-column: 2;
  grid-row: 3;
}
.sky-left {
  grid-column: 1;
  grid-row: 2;
}
.sky-right {
  grid-column: 3;
  grid-row: 2;
}
.sky-clues {
  display: grid;
  gap: 0;
  color: var(--warn);
  font-family: var(--mono);
  font-weight: 700;
  font-size: calc(var(--cell) * 0.42);
}
.sky-top,
.sky-bottom {
  grid-auto-flow: column;
}
.sky-top span,
.sky-bottom span {
  width: var(--cell);
  height: calc(var(--cell) * 0.55);
  display: grid;
  place-items: center;
}
.sky-left,
.sky-right {
  grid-auto-flow: row;
}
.sky-left span,
.sky-right span {
  width: calc(var(--cell) * 0.55);
  height: var(--cell);
  display: grid;
  place-items: center;
}

.board-caption {
  margin-top: 0.75rem;
  text-align: center;
  color: var(--text-dim);
  font-size: 0.85rem;
  min-height: 1.2em;
}

.board-meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  margin-top: 0.5rem;
  min-height: 1.4em;
}

.timer {
  font-family: var(--mono);
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--accent);
  min-width: 3ch;
}

.best-line {
  margin-top: 0.25rem;
  text-align: center;
  font-size: 0.78rem;
  color: var(--text-dim);
}
.best-line[hidden] {
  display: none;
}

.status {
  min-height: 1.4em;
  font-weight: 600;
}

.status.ok {
  color: var(--good);
}
.status.err {
  color: var(--bad);
}
.status.info {
  color: var(--accent);
}

/* ——— Cells ——— */
.cell {
  position: relative;
  width: var(--cell);
  height: var(--cell);
  display: grid;
  place-items: center;
  border: 1px solid var(--border);
  background: var(--bg-elev);
  cursor: pointer;
  font-family: var(--mono);
  font-size: calc(var(--cell) * 0.48);
  font-weight: 650;
  line-height: 1;
}

.cell .cell-content {
  display: grid;
  place-items: center;
  width: 100%;
  height: 100%;
  line-height: 1;
}

.cell.size-4 {
  --cell: 3.1rem;
}
.cell.size-6 {
  --cell: 2.9rem;
}
.cell.size-9 {
  --cell: 2.55rem;
}
.cell.size-12 {
  --cell: 2.05rem;
  font-size: 0.95rem;
}

.cell.given {
  background: var(--given-bg);
  color: var(--text);
}

.cell.user {
  background: var(--user-bg);
  color: var(--accent);
}

.cell.selected {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
  z-index: 2;
}

.cell.peer {
  background: var(--peer-bg);
}

.cell.same-value {
  background: var(--same-bg);
}

.cell.conflict {
  color: var(--bad) !important;
  background: var(--conflict-bg) !important;
}

.cell.notes-mode {
  cursor: crosshair;
}

.cell .notes {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  width: 100%;
  height: 100%;
  padding: 2px;
  font-size: calc(var(--cell) * 0.22);
  font-weight: 600;
  color: var(--text);
  line-height: 1;
}

.cell.size-12 .notes {
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(3, 1fr);
}

.cell .notes span {
  display: grid;
  place-items: center;
}

.cell .notes span.on {
  color: var(--text);
  font-weight: 700;
}

.cell .notes span.on.auto {
  color: var(--accent);
}

/* Block / box borders (sudoku-style) */
.cell.box-right {
  border-right-width: 2px;
  border-right-color: var(--border-strong);
}
.cell.box-bottom {
  border-bottom-width: 2px;
  border-bottom-color: var(--border-strong);
}
.cell.box-left {
  border-left-width: 2px;
  border-left-color: var(--border-strong);
}
.cell.box-top {
  border-top-width: 2px;
  border-top-color: var(--border-strong);
}

/* Calcudoku cages */
.cell.cage-c {
  outline: 1px solid var(--cage);
  outline-offset: -1px;
}
.cell.cage-c.cage-top {
  outline-top-width: 2px;
}
.cell.cage-c.cage-bottom {
  border-bottom: 2px solid var(--cage);
}
.cell.cage-c.cage-left {
  border-left: 2px solid var(--cage);
}
.cell.cage-c.cage-right {
  border-right: 2px solid var(--cage);
}

.cell .cage-label {
  position: absolute;
  top: 1px;
  left: 3px;
  font-size: 0.62rem;
  font-weight: 700;
  color: var(--warn);
  letter-spacing: 0.01em;
  pointer-events: none;
}

/* Futoshiki inequalities */
.cell .ineq {
  position: absolute;
  font-size: 0.85rem;
  color: var(--warn);
  font-weight: 700;
  pointer-events: none;
  line-height: 1;
}

.cell .ineq.right {
  right: -0.42rem;
  top: 50%;
  transform: translateY(-50%);
  z-index: 3;
}
.cell .ineq.below {
  bottom: -0.42rem;
  left: 50%;
  transform: translateX(-50%);
  z-index: 3;
}

.board.has-ineq {
  gap: 0.45rem;
}

/* ——— Side panel ——— */
.side-panel {
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
}

.tool-group {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.85rem;
}

.tool-group h2 {
  margin: 0 0 0.55rem;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-dim);
}

.tool-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 0.45rem;
}

.tool-row:last-child {
  margin-bottom: 0;
}

.tool-row .btn {
  flex: 1 1 auto;
  min-width: 5.5rem;
  font-size: 0.85rem;
}

.numpad {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.4rem;
}

.numpad.cols-3 {
  grid-template-columns: repeat(3, 1fr);
}
.numpad.cols-4 {
  grid-template-columns: repeat(4, 1fr);
}

.numpad .digit {
  aspect-ratio: 1.15;
  font-family: var(--mono);
  font-size: 1.15rem;
  font-weight: 700;
  background: var(--bg-soft);
}

.numpad .digit.wide {
  grid-column: 1 / -1;
  aspect-ratio: auto;
  font-size: 0.85rem;
  font-weight: 600;
}

.hint-line {
  margin: 0.6rem 0 0;
  font-size: 0.78rem;
  color: var(--text-dim);
  line-height: 1.4;
}

kbd {
  padding: 0.05rem 0.3rem;
  border: 1px solid var(--border-strong);
  border-bottom-width: 2px;
  border-radius: 4px;
  background: var(--bg-soft);
  font-family: var(--mono);
  font-size: 0.75em;
}

.legend {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.35rem;
  font-size: 0.85rem;
  color: var(--text-dim);
}

.legend li {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.swatch {
  width: 0.9rem;
  height: 0.9rem;
  border-radius: 3px;
  border: 1px solid var(--border);
  display: inline-block;
}

.swatch.given {
  background: var(--given-bg);
}
.swatch.user {
  background: var(--user-bg);
  border-color: var(--accent);
}
.swatch.note {
  background: var(--bg-elev);
  box-shadow: inset 0 0 0 1px var(--note);
}
.swatch.conflict {
  background: var(--conflict-bg);
  border-color: var(--bad);
}
.swatch.cage {
  background: transparent;
  border: 2px solid var(--cage);
}

.shortcuts dl {
  margin: 0;
  display: grid;
  gap: 0.3rem;
  font-size: 0.8rem;
}

.shortcuts dl > div {
  display: grid;
  grid-template-columns: 7.5rem 1fr;
  gap: 0.4rem;
}

.shortcuts dt {
  color: var(--accent);
  font-family: var(--mono);
  font-size: 0.75rem;
}

.shortcuts dd {
  margin: 0;
  color: var(--text-dim);
}

.footer {
  margin-top: 1.25rem;
  text-align: center;
  color: var(--text-dim);
  font-size: 0.82rem;
  line-height: 1.45;
}

@media (max-width: 520px) {
  :root {
    --cell: 2.15rem;
  }
  .cell.size-12 {
    --cell: 1.55rem;
  }
  .app {
    padding: 0.75rem;
  }
}

/* ───────── version / updates ───────── */

/* In the layout flow above the header, so it never covers the grid or controls. */
.update-banner {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.5rem 0.9rem;
  margin-bottom: 1rem;
  padding: 0.55rem 0.9rem;
  border: 1px solid var(--accent);
  border-radius: var(--radius);
  background: var(--accent-soft);
  color: var(--text);
  font-weight: 600;
  font-size: 0.92rem;
  text-align: center;
  animation: bannerSlide 0.3s ease-out;
}
.update-banner[hidden] {
  display: none;
}
.update-banner .update-warn {
  color: var(--warn);
  font-weight: 500;
}
.update-banner .btn {
  padding: 0.35rem 0.8rem;
}
@keyframes bannerSlide {
  from {
    transform: translateY(-0.5rem);
    opacity: 0;
  }
}

.footer .version-line {
  display: block;
  margin-top: 0.35rem;
  font-size: 0.72rem;
  opacity: 0.75;
}
.footer .version-line[hidden] {
  display: none;
}

.whats-new-dialog {
  max-width: min(26rem, calc(100vw - 2rem));
  padding: 1.1rem 1.25rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-elev);
  color: var(--text);
}
.whats-new-dialog::backdrop {
  background: color-mix(in srgb, var(--bg) 70%, black);
}
.whats-new-dialog h2 {
  margin: 0 0 0.5rem;
  font-size: 1.1rem;
}
.whats-new-dialog form {
  display: flex;
  flex-direction: column;
}
.whats-new-dialog .btn {
  align-self: flex-end;
}
.whats-new {
  margin: 0.4rem 0 0.9rem;
  padding-left: 1.2rem;
  line-height: 1.45;
}
.whats-new li + li {
  margin-top: 0.4rem;
}
.whats-new-dialog .version-line {
  margin: 0 0 0.8rem;
  font-size: 0.75rem;
  color: var(--text-dim);
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 1rem;
  transform: translateX(-50%);
  max-width: calc(100vw - 2rem);
  padding: 0.5rem 0.9rem;
  border: 1px solid var(--accent);
  border-radius: 999px;
  background: var(--bg-elev);
  color: var(--text);
  font-size: 0.85rem;
  pointer-events: none;
  box-shadow: 0 6px 20px var(--shadow);
}
.toast[hidden] {
  display: none;
}